Most patients with hypoglycemia have mild symptoms, and the symptoms will disappear after correcting the blood glucose level without leaving sequelae, but some patients with long-term repeated hypoglycemia or severe hypoglycemia not corrected in time may still lead to some serious complications. Brain complications: The initial change of hypoglycemia is to cause asymmetric increase of blood flow in brain tissue, if it cannot be corrected in time, followed by brain tissue edema, at this time, serious neurological hypoglycemia syndrome can appear, and the above changes can be recovered after timely correction, without leaving permanent damage, but if hypoglycemia persists or recurring, it can cause degeneration and punctate necrosis of brain cells in gray matter part. If hypoglycemia is very serious and not corrected for a long time, it can cause necrosis and softening of large brain tissue, resulting in brain atrophy and dementia. Cardiac complications: When hypoglycemia attacks, the excitation of sympathetic and chromophobic system will lead to accelerated heart rate or sinus tachycardia, as well as atrial premature beats, supraventricular tachycardia, ventricular premature beats, short burst ventricular tachycardia and other kinds of arrhythmias. Angina pectoris or even myocardial infarction is often induced by hypoglycemic episodes in people with coronary artery disease. Painless myocardial infarction may occur in patients with diabetic neuropathy or in those who have a reduced response to pain in old age and is easily overlooked, which is one of the major causes of sudden death in diabetic patients. Other complications: For example, Somogyi reaction, which is an alternating episode of nighttime hypoglycemia and daytime hyperglycemia, can worsen diabetes and even ketosis. Repeated episodes of hypoglycemia can reduce the alert symptoms of hypoglycemic episodes and promote the production of unobserved hypoglycemia. Hypoglycemic coma secretions or foreign body accidentally inhaled into the trachea can easily lead to lung abscess or other lung infections. Once Somogyi reaction occurs in gestational diabetes, the condition will be more severe and will not return to normal even after delivery. Therefore, although most hypoglycemia does not leave sequelae, serious cases can still lead to complications, and patients should promptly deal with and find the cause of the disease and prevent it in time.